1. Field of the Invention
This invention relates to an image display apparatus provided with an liquid crystal display element and a back light for lighting the liquid crystal display element, and relates to an light image forming unit, and light enlarging unit, or optical parts which are components of the image display apparatus.
2. Description of the Related Art
With rapid progress of computers, recently the resolution of the image display apparatus has been improved rapidly and along with the size of the display screen has been increased.
Though the cathode ray tube type image display apparatus, which has been used conventionally, is excellent in resolution, the weight and power consumption increases in proportion to the resolution, and also price has risen. Because the large size display screen involves increased weight and depth, the degree of high resolution and size of display screen is naturally limited.
Significant progress has been conducted in the aspect of resolution of the liquid crystal display element type image display apparatus and the high resolution has been realized always in conformity with market needs, however not so rapid progress has been conducted in the aspect of size of display screen because the liquid crystal element is fabricated almost by mean of semiconductor process.
To realize the liquid crystal display element type large size display screen, various trials have been made. Among these trials, a method in which a small size display screen is enlarged and projected by use of a projection lens has been practically progressed particularly. However, this method requires a long projection distance. A large size display screen by means of the method loses the advantage of the liquid crystal display element, namely the advantage of thinness of the liquid crystal display element.
Some alternative methods in which liquid crystal panels are jointed without seam have been proposed. For example, Japanese Unexamined Patent Publication No. Hei 5-188340 discloses a method in which a liquid crystal panel is provided with an image forming unit and enlarging unit and the liquid crystal panel are enlarged only to the magnitude to cover the seam portion between adjacent liquid crystal panels. In this conventional method, the thinning is easy because the magnitude of enlargement is small. An image display apparatus associated with the present invention is described with reference to FIG. 23 and FIG. 24.
FIG. 23 is a plan view of an image display apparatus for covering the seam of liquid crystal panels, and FIG. 24 is a cress sectional view along the line A-A1 in FIG. 23. In FIG. 23 and FIG. 24, 51a and 51b denote transmission type liquid crystal display elements, 52 denotes a back light for lighting the above-mentioned liquid crystal display element, 53 denotes a cathode ray tube which is an component of the back light, 54 denotes a means for narrowing the divergent angle of output light of the back light, namely divergent angle control means, 55a and 55b denote image forming unit for projecting the display image (not shown in the drawing) on the liquid crystal display elements 51a and 51b to form an erect life-size real image(that is, erect real image having roughly same size in the embodiment), 56a and 56b denote enlarging units for enlarging the projected erect real image formed by 55a and 55b, 57 denotes a back side projection type screen, and 58 denotes a chassis for containing these parts therein.
Next, the operation of component parts is described. The back light 52 lights the transmission type liquid crystal display elements 51a and 51b with a light emitted from the cathode ray tube 53 which is a component of the back light 52. However the transmission type liquid crystal display element is disadvantageous in view angle characteristic and the contrast is inverted on the portion where the light is irradiated with an angle larger than a certain angle. To prevent the contrast inversion, the divergent angle control means 54 for narrowing the divergent angle of output light of the back light is provided between the back light 52 and the transmission type liquid crystal display elements 51a and 51b. As the divergent angle control means 54 for narrowing the divergent angle of the output light of the back light, a means in which the angle of light having the incident angle within a certain angle range is narrowed and the light having the incident angle exceeding the certain angle range is returned back so as not to be output light has been known. According to Fujitsu Giho (FUJITSU. 47, 4, (07, 1996), p355), the same effect is realized by arranging light transmissible cones. As the result, the display image displayed on the transmission type liquid crystal display elements 51a and 51b has a predetermined divergent angle. A display image displayed on the liquid crystal display elements 51a and 51b by use of image forming units 55a and 55b having an image taking angle larger than the divergent angle is projected to form an erect life-size image. The image forming units 55a and 55b are disclosed in, for example, Japanese Unexamined Patent Publication No. Sho 64-17017. In the application, the divergent angle control means is realized by a rod lens eye structure comprising many connected lenses, each connected lens comprises two lenses connected longitudinally. A display image projected by means of the image forming units 55a and 55b is enlarged by means of the enlarging units 56a and 56b, and an image is formed on the back projection type screen 57. As the enlarging units 56a and 56b, a concave Fresnel lens which are disclosed in, for example, Japanese Unexamined Patent Publication No. Hei 9-96704 may be used.
A plurality of projection units described herein above are arranged so that respective projection images are joined without seam on the back projection type screen 57 to thereby obtain a large size high resolution image.
However, rod lens eyes are used as the image forming units 55a and 55b in the conventional art described herein above, the image forming units 55a and 55b having a rod lens array is not only expensive but also not suitable for mass-production in association with the manufacturing process of rod lens arrays.
To solve the above-mentioned problem, a pair of micro-lens arrays disclosed in, for example, Japanese Unexamined Patent Publication No. Hei 9-274177 may be used because the micro-lens array can be easily mass-produced by means of die molding. However, manufacturing is involved in difficult problem because it is difficult to match the optical axis of the micro-lenses on the incident and emission surfaces of respective micro-lens array of a pair of micro-lens arrays and also it is difficult to match the optical axis of respective micro-lenses of two micro-lens arrays. Particularly in the case of a large size micro-lens array, it is required to fit a pair of micro-lens arrays on the entire surface, however a thin-walled large size molded product is apt to deform easily depending on the environmental humidity and temperature condition and large size micro-lens arrays can not be tightly fit invariantly.
Furthermore, the conventional art described herein above requires the narrow divergent angle of the output light from the back light 52. The output light of the cathode ray tube 53 which is an component of the back light 52 has significantly wide divergent angle, and the narrowing of the divergent angle causes serious reduction of the efficiency. Furthermore, the means 54 for narrowing the divergent angle of the output light of a back light having the above-mentioned arranged light transmissible cones has a large depth, therefore the means 54 causes the loss of the advantage of the liquid crystal display apparatus namely thin depth.
It is an object of the present invention to solve the above-mentioned problems and to provides a thin efficient image display apparatus and an image forming unit, an enlarging unit, or optical parts including these components which are components of the image display apparatus.
It is another object of the present invention to provide an image forming unit for correcting deformation due to molding, optical parts including the image forming unit, and a image display apparatus which uses the image forming unit.
It is yet another object of the present invention to provide an image forming unit, an enlarging unit, optical parts including the image forming unit, and an image display apparatus which uses the image forming unit which prevents stray light even though the divergent angle of the output light of the back light is large.
To achieve the purpose of the present invention, in the first invention, an image display apparatus comprises a transmission type liquid crystal display element, a back light for lighting the liquid crystal display element, optical parts including an image forming unit for projecting a display image (or display image information)on the liquid crystal display element, and a back projection type screen for displaying a projection image, wherein the optical parts comprises an incident side micro-lens array, a emission side micro-lens array, the first light transmissible plate warped convexly toward the incident side micro-lens array, and the second light transmissible plate warped convexly toward the emission side micro-lens array, and the incident side micro-lens array and the emission side micro-lens array are held between the first and second light transmissible plates and ends of these components are fixed or semi-fixed together.
In the first invention, peripheries of the incident side micro-lens array and the emission side micro-lens array are adhered together. Furthermore, peripheries of the incident side micro-lens array and the emission side micro-lens array are adhered together by means of any one of heat melting type film adhesive, photo-setting type adhesive, and ultrasonic melting adhesion.
In the first invention, the second light transmissible plate is an enlarging unit. The enlarging unit is preferably a concave Fresnel lens. The concave Fresnel lens is coated with moisture proofing material. The concave Fresnel lens consists of a material which is less moisture absorptive than polymethylmethacrylate resin. In the first invention, the concave Fresnel lens is disposed so that the Fresnel surface is in contact with the emission side micro-lens array. Projections having flat end are provided on the top of Fresnel of the concave Fresnel lens, and shading portions for shading are provided on each top of the projections. The size of the projections of the concave Fresnel lens is equal for all the projections, or the size of the projections may decrease gradually from the peripheral area to the center area. A light reduction filter is provided on the center area of the concave Fresnel lens where the projection is not provided.
In the first invention, a U-shaped adapter is provided, ends of the incident side micro-lens array, the emission side micro-lens array, the first light transmissible plate, and the second light transmissible plate are inserted into the space of the U-shaped adapter, tightened with both ends of the U-shaped adapter, and semi-fixed with the adapter. Otherwise, edges of the incident side micro-lens array, the emission side micro-lens array, and the first and second light transmissible plates are adhered, melting adhered, or pressure sensitively adhered. The plate thickness of the first light transmissible plate is preferably equal to that of the second light transmissible plate. The first and second light transmissible plates consist of the same material. The warping magnitude of the first and second light transmissible plates is preferably equal each other.
In the first invention, a stop array is provided between the incident side micro-lens array and the emission side micro-lens array. The stop array is a shading plate having a plurality of light passing portions. The incident side and emission side micro-lens arrays comprise lens groups respectively, the number of lens groups is approximately equal to the number of effective light passing portions of the stop array. The optical axes of the lens groups are coincident with the positions of the light passing portions. The diameter of the light passing portion provided on the stop array may be larger on the peripheral area than on the center area of the stop array. The coefficient of linear thermal expansion of the material of the stop array is approximately equal preferably to that of the material of the incident side and emission side micro-lens arrays. The material used for the stop array is photoresist material which is coated at least on one of the incident side micro-lens array and the emission side micro-lens array, and portions coincident with the optical axes of the lens groups are removed.
In the second invention, an image display apparatus comprises a transmission type liquid crystal display element, a back light for lighting the liquid crystal display element, optical parts including an image forming unit for projecting a display image(or display image information) on the liquid crystal display element, and a back projection type screen for displaying a projection image, wherein the optical parts comprises the image forming unit comprising an incident side micro-lens array and a emission side micro-lens array, an enlarging unit warped convexly toward the image forming unit side, and a light transmissible support plate warped convexly toward the image forming unit side, and the image forming unit is held between the enlarging unit warped convexly toward the image forming unit side and the light transmissible support plate warped convexly toward the image forming unit side and the peripheries of the enlarging unit and the light transmissible support plate are fixed or semi-fixed.
In the second invention, peripheries of the incident side micro-lens array and the emission side micro-lens array are adhered together. Peripheries of the incident side micro-lens array and the emission side micro-lens array are adhered together by means of any one of heat melting type film adhesive, photo-setting type adhesive, and ultrasonic melting adhesion.
In the second invention, the enlarging unit is a concave Fresnel lens. The concave Fresnel lens may be coated with moisture proofing material. The concave Fresnel lens consists of a material which is less moisture absorptive than polymethylmethacrylate resin. In the second invention, the concave Fresnel lens is disposed so that the Fresnel surface is in contact with the emission side micro-lens array. Projections having flat end are provided on the top of Fresnel of the concave Fresnel lens, and shading portions for shading are provided on each top of the projections. The size of the projections of the concave Fresnel lens is equal for all the projections, or the size of the projections may decrease gradually from the peripheral area to the center area. A light reduction filter is provided on the center area of the concave Fresnel lens where the projection is not provided.
In the second invention, a U-shaped adapter is provided, ends of the incident side micro-lens array, the emission side micro-lens array, the first light transmissible plate, and the second light transmissible plate are inserted into the space of the U-shaped adapter, tightened with both ends of the U-shaped adapter, and semi-fixed with the adapter. Otherwise, edges of the incident side micro-lens array, the emission side micro-lens array, the enlarging unit, and the light transmissible plate are adhered or pressure sensitively adhered. The plate thickness of the enlarging unit is approximately equal to that of the light transmissible support plate. The material of the enlarging unit may be the same as that of the light transmissible support plate. The warp magnitude of the enlarging unit is preferably approximately equal to that of the light transmissible support plate.
In the second invention, a stop array is provided between the incident side micro-lens array and the emission side micro-lens array. The stop array is a shading plate having a plurality of light passing portions. The incident side and emission side micro-lens arrays comprise lens groups respectively, the number of lens groups is approximately equal to the number of effective light passing portions of the stop array. The optical axes of the lens groups are preferably coincident with the positions of the light passing portions. The diameter of the light passing portion provided on the stop array may be larger on the peripheral area than on the center area of the stop array.
In the second invention, the coefficient of linear thermal expansion of the material of the stop array is approximately equal preferably to that of the material of the incident side and emission side micro-lens arrays. The material used for the stop array is photoresist material which is coated at least on one of the incident side micro-lens array and the emission side micro-lens array, and portions coincident with the optical axes of the lens groups are removed.
In the third invention, optical parts used for projecting a display image(or display image information) displayed on a liquid crystal display element on a screen by use of a back light for lighting the liquid crystal display element comprise an incident side micro-lens array, a emission side micro-lens array, the first light transmissible plate warped convexly toward the incident side micro-lens array side, and the second light transmissible plate warped convexly toward the emission side micro-lens array, wherein the incident side micro-lens array and the emission side micro-lens array are held between the first and second light transmissible plates, and edges of these components are fixed or semi-fixed.
In the third invention, peripheries of the incident side micro-lens array and the emission side micro-lens array are adhered together. Furthermore, the incident side micro-lens array and the emission side micro-lens array are adhered together at the edges of the incident side and the emission side micro-lens arrays by means of any one of heat melting type film adhesive, photo-setting type adhesive, and ultrasonic melting adhesion.
In the third invention, the second light transmissible plate is an enlarging unit. The enlarging unit is a concave Fresnel lens. The concave Fresnel lens is preferably coated with moisture proofing material. The concave Fresnel lens may consist of a material which is less moisture absorptive than polymethylmethacrylate resin.
In the third invention, the concave Fresnel lens is disposed so that the Fresnel surface is in contact with the emission side micro-lens array. Projections having flat end are provided on the top of Fresnel of the concave Fresnel lens, and shading portions for shading are provided on each top of the projections. The size of the projections of the concave Fresnel lens is equal for all the projections, or the size of the projections may decrease gradually from the peripheral area to the center area. A light reduction filter is provided on the center area of the concave Fresnel lens where the projection is not provided.
In the third invention, a U-shaped adapter is provided, ends of the incident side micro-lens array, the emission side micro-lens array, the first light transmissible plate, and the second light transmissible plate are inserted into the space of the U-shaped adapter, tightened with both ends of the U-shaped adapter, and semi-fixed with the adapter. Otherwise, edges of the incident side micro-lens array, the emission side micro-lens array, and the first and second light transmissible plates are adhered or pressure sensitively adhered.
Furthermore, the plate thickness of the first light transmissible plate is preferably equal to that of the second light transmissible plate. The first and second light transmissible plates consist of the same material. The warping magnitude of the first and second light transmissible plates is preferably equal each other.
In the third invention, a stop array is provided between the incident side micro-lens array and the emission side micro-lens array. The stop array is a shading plate having a plurality of light passing portions. The incident side and emission side micro-lens arrays comprise lens groups respectively, the number of lens groups is approximately equal to the number of effective light passing portions of the stop array. The optical axes of the lens groups are coincident with the positions of the light passing portions. The diameter of the light passing portion provided on the stop array may be larger on the peripheral area than on the center area of the stop array. The coefficient of linear thermal expansion of the material of the stop array is approximately equal preferably to that of the material of the incident side and emission side micro-lens arrays. The material used for the stop array is photoresist material which is coated at least on one of the incident side micro-lens array and the emission side micro-lens array, and portions coincident with the optical axes of the lens groups are removed.
In the fourth invention, optical parts used for projecting a display image(or display image information) displayed on a liquid crystal display element on a screen by use of a back light for lighting the liquid crystal display element comprise the image forming unit comprising an incident side micro-lens array and a emission side micro-lens array, an enlarging unit warped convexly toward the image forming unit side, and a light transmissible support plate warped convexly toward the image forming unit side, wherein the image forming unit is held between the enlarging unit warped convexly toward the image forming unit side and the light transmissible support plate warped convexly toward the image forming unit side, and the peripheries of the enlarging unit and the light transmissible support plate are fixed or semi-fixed.
In the fourth invention, the incident side micro-lens array and the emission side micro-lens array are adhered together at the peripheries of the incident side and emission side micro-lens arrays. Peripheries of the incident side micro-lens array and the emission side micro-lens array are adhered together by means of any one of heat melting type film adhesive, photo-setting type adhesive, and ultrasonic melting adhesion.
In the fourth invention, the enlarging unit is a concave Fresnel lens. The concave Fresnel lens may be coated with moisture proofing material. The concave Fresnel lens consists of a material which is less moisture absorptive than polymethylmethacrylate resin.
In the fourth invention, the concave Fresnel lens is disposed so that the Fresnel surface is in contact with the emission side micro-lens array. Projections having flat end are provided on the top of Fresnel of the concave Fresnel lens, and shading portions for shading are provided on each top of the projections. The size of the projections of the concave Fresnel lens is equal for all the projections, or the size of the projections may decrease gradually from the peripheral area to the center area. A light reduction filter is provided on the center area of the concave Fresnel lens where the projection is not provided.
In the fourth invention, a U-shaped adapter is provided, ends of the incident side micro-lens array, the emission side micro-lens array, the first light transmissible plate, and the second light transmissible plate are inserted into the space of the U-shaped adapter, tightened with both ends of the U-shaped adapter, and may be semi-fixed with the adapter. Otherwise, edges of the incident side micro-lens array, the emission side micro-lens array, the enlarging unit, and the light transmissible plate may be adhered or pressure sensitively adhered.
In the fourth invention, the plate thickness of the enlarging unit may be approximately equal to that of the light transmissible support plate. The material of the enlarging unit may be the same as that of the light transmissible support plate. The warp magnitude of the enlarging unit is preferably approximately equal to that of the light transmissible support plate.
In the fourth invention, a stop array is provided between the incident side micro-lens array and the emission side micro-lens array. The stop array is a shading plate having a plurality of light passing portions. The incident side and emission side micro-lens arrays comprise lens groups respectively, the number of lens groups may be approximately equal to the number of effective light passing portions of the stop array. The optical axes of the lens groups are preferably coincident with the positions of the light passing portions. The diameter of the light passing portion provided on the stop array may be larger on the peripheral area than on the center area of the stop array. The coefficient of linear thermal expansion of the material of the stop array is approximately equal preferably to that of the material of the incident side and emission side micro-lens arrays. The material used for the stop array is photoresist material which is coated at least on one of the incident side micro-lens array and the emission side micro-lens array, and portions coincident with the optical axes of the lens groups are removed.
In the fifth invention, peripheries of the incident side micro-lens array and the emission side micro-lens array are adhered by means of any one of heat melting type film adhesive, photo-setting type adhesive, or ultrasonic melting adhesion. A stop array may be provided between the incident side micro-lens array and the emission side micro-lens array. The stop array may be a shading plate having a plurality of light passing portions. The incident side and emission side micro-lens arrays comprise lens groups respectively, the number of lens groups may be approximately equal to the number of effective light passing portions of the stop array. The optical axes of the lens groups are preferably coincident with the positions of the light passing portions. The diameter of the light passing portion provided on the stop array may be larger on the peripheral area than on the center area of the stop array. The coefficient of linear thermal expansion of the material of the stop array may be approximately equal to that of the material of the incident side and emission side micro-lens arrays. The material used for the stop array is photoresist material which is coated at least on one of the incident side micro-lens array and the emission side micro-lens array, and portions coincident with the optical axes of the lens groups are removed.
In the sixth invention, an enlarging unit comprises a concave Fresnel lens having a Fresnel on the surface disposed facing on the incident side of an image forming unit.
In the sixth invention, the concave Fresnel lens is coated with moisture proofing material. The concave Fresnel lens consists of a material which is less moisture absorptive than polymethylmethacrylate resin.
In the sixth invention, projections are provided on the top of Fresnel of the concave Fresnel lens, and shading portions for shading are provided on each top of the projections. The size of the projections of the concave Fresnel lens is equal for all the projections. Otherwise, the size of the projections of the concave Fresnel lens may decrease gradually from the peripheral area to the center area. A light reduction filter is preferably provided on the center area of the concave Fresnel lens where the projection is not provided.
In the seventh invention, an image display apparatus comprises a transmission type liquid crystal display element, a back light for lighting said liquid crystal display element, optical parts including an image forming unit for projecting display image information(or a display image) on said liquid crystal display element, and a back projection type screen for displaying a projection image. Said optical parts comprises an incident side micro-lens array, a emission side micro-lens array, a first light transmissible plate having elasticity, and the second light transmissible plate having elasticity. Wherein said incident side micro-lens array and said emission side micro-lens array are held between said first and second light transmissible plates, and are elastically pressed by said first and second light transmissible plates.
In the eighth invention, an image display apparatus comprises a transmission type liquid crystal display element, a back light for lighting said liquid crystal display element, optical parts including an image forming unit for projecting display image information(or a display image) on said liquid crystal display element, and a back projection type screen for displaying a projection image. Said optical parts comprises said image forming unit comprising an incident side micro-lens array and a emission side micro-lens array, an enlarging unit having elasticity, and a light transmissible support plate having elasticity. Wherein said image forming unit is held between said enlarging unit and said light transmissible support plate, and is elastically pressed by said enlarging unit and said light transmissible support plate.
In the ninth invention, optical part is used for projecting display image information(or a display image) displayed on a liquid crystal display element on a screen by use of a back light for lighting said liquid crystal display element. Said optical parts comprises an incident side micro-lens array, a emission side micro-lens array, a first light transmissible plate having elasticity, and a second light transmissible plate having elasticity. Wherein said incident side micro-lens array and said emission side micro-lens array are held between said first and second light transmissible plates, and are elastically pressed by said first and second light transmissible plates.
In the tenth invention, optical part is used for projecting display image information displayed on a liquid crystal display element on a screen by use of a back light for lighting said liquid crystal display element. Said optical parts comprises said image forming unit comprising an incident side micro-lens array and a emission side micro-lens array, an enlarging unit having elasticity, and a light transmissible support plate having elasticity. Wherein said image forming unit is held between said enlarging unit and said light transmissible support plate, and are elastically pressed by said enlarging unit and said light transmissible support plate.